1. Field of the Invention
The present invention relates to a method of manufacturing a revolving whetstone and a revolving whetstone manufactured by the same, in particular, it relates to a method of manufacturing revolving whetstones such as an offset type revolving whetstone for polishing and grinding (hereinafter, referred to as “polishing”), a flat type revolving whetstone for cutting, a disk revolving whetstone for polishing, a revolving whetstone with sandpaper for polishing and the like, and revolving whetstones manufactured by the same.
2. Description of the Related Art
Conventionally, the offset type revolving whetstone for polishing, the flat type revolving whetstone for cutting, the disk revolving whetstone for polishing, the revolving whetstone with sandpaper for polishing and the like have been known widely (for example, refer to Japanese Patent Application Laid-Open Publication No. H5-51562).
An example of the revolving whetstone known in the conventional art disclosed in Japanese Patent Application Laid-Open Publication No. H5-51562 and the like is shown in FIG. 8 and FIG. 9. In the figures, a revolving whetstone 51 is constituted of a disk-shaped whetstone body 52 and a reinforcing metal fitting 54 made of a metal attached to a whetstone center hole 53 of the whetstone body 52. In addition, the whetstone center hole 53 is an insertion hole for a whetstone driving shaft such as a hand grinder and the like, and, the reinforcing metal fitting 54 is arranged for reinforcement of the whetstone center hole 53.
The whetstone body 52 is made by mixing an abrasive grain (for example, bauxite) and binder resin, and molding and sintering the same, and has a central portion 52a in which the whetstone center hole 53 is arranged and an effective whetstone circular portion 52b that is arranged in the circumferential outside of the central portion 52a as one body, and in addition, a glass cloth reinforcing member 55 is inserted into the inside of the central portion 52a and the effective whetstone circular portion 52b. In addition, the reinforcing metal fitting 54 is made into one body with the whetstone body 52 at the time of molding the whetstone body 52.
Next, the case where the revolving whetstone 51 is attached to a hand grinder for use is explained. In the grinder to which the revolving whetstone 51 is attached, a whetstone driving shaft 62 protrudes from a grinder main body 61 as shown in FIG. 10, and a screw portion is formed in the end of the whetstone driving shaft 62, and the screw portion is so structured that a fastening nut 63 is screwed thereinto. In addition, a flange 62a and a whetstone engaging portion 62b are arranged at the portion near the root of the whetstone driving shaft 62.
When the revolving whetstone 51 is attached to the hand grinder, first, the whetstone engaging portion 62b that is arranged on the whetstone driving shaft 62 is inserted into the whetstone center hole 53, and one side of the revolving whetstone 51 is positioned to contact the flange 62a. Subsequently, the fastening nut 63 is screwed into the screw portion arranged in the end of the whetstone driving shaft 62 protruding from the other side of the revolving whetstone 51, and the revolving whetstone 51 is fastened together with the flange 62a. Thus, the revolving whetstone 51 is precisely centered and attached to the whetstone driving shaft 62.
The revolving whetstone 51 arranged to the grinder in this manner rotates together with the whetstone driving shaft 63, and is made to contact the surface of a workpiece to be polished 70 at the angle usually around 15 to 30 degrees and its polishing is carried out. In addition, the effective whetstone circular portion 52b is abraded as the polishing work goes on. When the abrasion progresses to the position shown by a mark Z in FIG. 9 (approximately 40%), it is judged that the revolving whetstone is out of its life time and is exchanged with a new revolving whetstone 51, and the old revolving whetstone 51 is disposed as an industrial waste. This exchange of the revolving whetstone 51 takes around 30 minutes in some work operations. Therefore, it has been desired to reduce the disposal amount of the industrial wastes, and, in addition, to expand the life time of the revolving whetstone 51, decrease the number of exchange times and improve the workability of the revolving whetstone.